Method of Milling With Shifting Tool Capabilities

ABSTRACT

A bottom hole assembly comprises a milling tool and associated drive motor with a shifting tool that is capable on deployment to selectively grab, shift and release from sliding sleeves when the bottom hole assembly is removed from the subterranean location. The shifting tool is preferably protected from the returning flow of cuttings to avoid erosion or clogging from the cuttings being circulated to the surface. The shifter tool can be of a known design to enable the milling of ball seats or entire plugs in the same trip as the operation of the sliding sleeve valves associated with the treatment operation so that the well can then be in position to commence production or injection once a suitable string and service packer are set in position. Typically the sleeves are open for the treatment and then closed after milling as the bottom hole assembly is removed.

FIELD OF THE INVENTION

The field of the invention is completion operation where the completion equipment needs to be removed by milling and sliding sleeve or other types of valves functioned to the open position prior to production or injection.

BACKGROUND OF THE INVENTION

In several treatment applications, notably fracturing, there are a series of ball seats used to sequentially frack portions of a producing interval. Typically these ball seats take progressively larger balls for zone isolation and pressure is applied against each seated ball in sequence going bottom up as progressively larger balls are dropped. At the end of the treatment, there is a need to remove the ball seats, a process that is usually accomplished by a separate trip with a mill attached to a downhole motor such as a progressing cavity motor of a known design. The cuttings are circulated out using the flow that initially drives the downhole motor. In some applications that use multiple plugs all the plugs can be milled out in a separate milling trip as shown in US 2013/0319669. In some applications where there are sleeves that are operated with known shifting tools, the milling trip is a separate trip from the trip where the shifting tool is used to open the sleeves for subsequent production or injection. This is illustrated in US 2013/0062066.

The present invention seeks to make the treatment process more efficient by saving rig time and shortening operations. Along those lines a bottom hole assembly (BHA) is proposed that will combine the milling and shifting of sleeves into a single trip rather than the separate trips that were required in the past. The sleeve shifter tool can be a part of the BHA and preferably mounted uphole from the downhole motor that drives the mill. The shifting tool is maintained retracted toward the mandrel of the BHA when the milling is undertaken and is then deployed to selectively grab, shift and release from the sliding sleeves as the BHA is pulled from the subterranean location after the milling is completed. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined by the appended claims.

SUMMARY OF THE INVENTION

A bottom hole assembly comprises a milling tool and associated drive motor with a shifting tool that is capable on deployment to selectively grab, shift and release from sliding sleeves when the bottom hole assembly is removed from the subterranean location. The shifting tool is preferably protected from the returning flow of cuttings to avoid erosion or clogging from the cuttings being circulated to the surface. The shifter tool can be of a known design to enable the milling of ball seats or entire plugs in the same trip as the operation of the sliding sleeve valves associated with the treatment operation so that the well can then be in position to commence production or injection once a suitable string and service packer are set in position. Typically the sleeves are open for the treatment and then closed after milling as the bottom hole assembly is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the bottom hole assembly being run into the well with the seats intact and the sliding sleeves open;

FIG. 2 is the view of FIG. 1 with the sliding sleeves still open and the ball seats milled;

FIG. 3 is the view of FIG. 2 showing the shifter tool closing the sliding sleeves as the bottom hole assembly is removed from the borehole.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 a string 10 delivers a bottom hole assembly that features a mill assembly 12 and a valve tool, preferably a shifting tool 14 located preferably uphole from the mill assembly 12. The mill assembly can be a mill of known design driven preferably by a fluid motor such as a progressing cavity pump also known as a Moineau pump. The motor driver, regardless of the known type that is used rotates the mill of the assembly 12 to mill out seats 16, 18 and 20 as seen by comparing FIGS. 1 and 2. Sliding sleeve valves 22, 24 and 26 are all preferably in the open position during the previous treatment operation that has concluded. They are shifted axially to the closed position against a stop that is not shown. Hitting the stop allows the shifting tool to flex and release from the respective sliding sleeves that was just shifted. Openings 28, 30 and 32 are in the open position for access to the surrounding formation for sequential treatment of portions of the formation in a known treatment method involving progressively larger balls landing in sequence on seats 16, 18 and 20 in a known treatment that progresses from the bottom and moves up toward the surface in the formation.

The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, emulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.

The milling assembly 12 advances in FIG. 2 past the last seat 20. Arrow 34 indicates the path through the annulus of return fluid that passes through the milling assembly 12 to drive the fluid motor and to flow through mill nozzles to aid in cuttings removal and ultimate circulation to the surface. The milling rate through the seats 16, 18 and 20 can be regulated from the surface as the cuttings coming up are monitored at the surface. The rate of milling penetration can thus be controlled to ensure that the cuttings are effectively removed. The shifter 14 can be protected during the milling process by positioning it in a mandrel recess or opening only to extend the shifter mechanism into an operating mode after all the milling is done. In another option, a protective sleeve 36 can be used that is selectively removable after milling to allow sequential engagement of the sliding sleeves 22, 24 and 26 to close them and release from each sliding sleeve as that sliding sleeve is put into the closed position. This operation closes openings 28, 30 and 32. At this point other well tests can be conducted before production or injection commences with a separate string and service packer that are set into position. The sleeve 36 can be physically shifted with pressure or mechanical force but the sleeve can also enable operation of the known shifting tool by simply disintegrating over time or with the influence of well fluids or thermal inputs. The sleeve 36 can be made of a controlled electrolytic material to accomplish such disintegration. The shifter can be a collet type device that puts a predetermined force on each sliding sleeve 22, 24 and 26 and moves such sleeves to a closed position against a stop at which time the added resistance fosters a release from that sleeve to allow the bottom hole assembly to keep moving out of the hole as subsequent sleeves are also closed.

It is preferred to locate the shifter 14 above the milling assembly 12 but the opposite orientation is also contemplated but is less preferred. What is shown is a one trip method where the barriers such as seats or isolation plugs can be milled out in a single trip going into the hole and some or all the sleeves or other types of tubular valves closed on the trip out of the hole with the milling assembly. It should be noted that the shifter 14 can be configured to engage all the sliding sleeves or less than all the sliding sleeves as required. One or more than one shifting tool can be used where one serves as a backup for another or where one is configured to operate different sliding sleeves or valves in the borehole.

The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: 

1. A completion method, comprising: running in a milling assembly and at least one valve tool into a borehole in a single trip; milling at least one barrier in the borehole and operating at least one valve that provides formation access from the borehole in said single trip.
 2. The method of claim 1, comprising: providing a ball seat as said at least one barrier.
 3. The method of claim 1, comprising: providing a sliding sleeve valve as said at least one valve.
 4. The method of claim 1, comprising: providing as said at least one valve a plurality of sliding sleeve valves.
 5. The method of claim 1, comprising: providing as said at least one barrier a plurality of ball seats.
 6. The method of claim 1, comprising: performing a treating operation against said ball seats that comprises at least one of hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding and cementing.
 7. The method of claim 1, comprising: locating the at least one valve tool uphole of the milling assembly.
 8. The method of claim 1, comprising: providing as said at least one valve tool a plurality of shifting tools that are identical or different.
 9. The method of claim 8, comprising: providing as said at least one valve a plurality of sliding sleeve valves; operating all or less than all of said valves with one or more than one of said shifting tools.
 10. The method of claim 1, comprising: providing a mill driven by a fluid motor as said milling assembly.
 11. The method of claim 1, comprising: protecting said shifting tool from cuttings circulated to the surface during operation of said milling assembly.
 12. The method of claim 11, comprising: using a protective sleeve to cover said shifting tool when cuttings are circulated to the surface during operation of said milling assembly.
 13. The method of claim 12, comprising: removing said sleeve from said shifting tool by disintegration of said sleeve, fluid pressure or mechanical force.
 14. The method of claim 13, comprising: making said sleeve of a controlled electrolytic material.
 15. The method of claim 1, comprising: providing as said at least one valve a plurality of sliding sleeve valves; axially shifting said sliding sleeves against respective stops with said at least one said shifting tool for an automatic release of said sliding sleeves. 